---
title: "Dinosaur hip groups"
description: "Use the traditional dinosaur groups Saurischia (lizard-hipped, including theropods and sauropods) and Ornithischia (bird-hipped, including Triceratops and Stegosaurus). Explain why one hip feature alo"
canonical: https://lightmysky.com/learn/science/dinosaur-hip-groups-mt_yrSdVrXrsF
source: https://lightmysky.com/learn/science/dinosaur-hip-groups-mt_yrSdVrXrsF.md
retrieved: 2026-11-12
---

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# Dinosaur hip groups

Use the traditional dinosaur groups Saurischia (lizard-hipped, including theropods and sauropods) and Ornithischia (bird-hipped, including Triceratops and Stegosaurus). Explain why one hip feature alone may not identify a group.

Subject: Science · Area: Dinosaurs & Paleontology · Ages 9 to 11
Page: https://lightmysky.com/learn/science/dinosaur-hip-groups-mt_yrSdVrXrsF

## Ready when they can

- Name the two major dinosaur groups: Saurischia and Ornithischia
- Explain that the traditional group names refer to hip structure, but a backward-pointing pubis alone does not identify a dinosaur's group
- Correctly classify at least two dinosaurs into each group (e.g. T. rex = Saurischia, Triceratops = Ornithischia)

## Lesson: Lizard hips and bird hips

You have met T. rex, Brachiosaurus, Triceratops and Stegosaurus. Naming identifies a dinosaur. Classification puts dinosaurs into groups. A group can contain smaller groups. Traditional dinosaur classification uses two groups: Saurischia, meaning 'lizard-hipped,' and Ornithischia, meaning 'bird-hipped.' Their names refer to hip bones, including a bone called the pubis. Food and body size do not define these groups.

**Example.** Saurischia includes theropods, such as T. rex, and sauropods, such as Brachiosaurus. T. rex ate meat, while Brachiosaurus ate plants. Many saurischians had a pubis that pointed forward. Different foods did not put these two dinosaurs in different hip groups.

**Example.** Ornithischia includes Triceratops and Stegosaurus. In these dinosaurs, part of the pubis points backward. This feature gave the group its name, 'bird-hipped.' The name does not mean that these dinosaurs were birds.

*(drawing: T. rex and Brachiosaurus belong to Saurischia. Triceratops and Stegosaurus belong to Ornithischia.)*

Living birds are dinosaurs descended from theropods in Saurischia. Some saurischians also had a backward-pointing pubis. So a backward-pointing pubis alone does not prove a dinosaur belongs to Ornithischia. Scientists compare several bones and other features to study relationships.

**Recap.** Saurischia includes T. rex and Brachiosaurus. Ornithischia includes Triceratops and Stegosaurus. A backward-pointing pubis alone cannot identify the group.

*Lesson, questions and flashcards written for this dataset.*

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Famous Dinosaur Species](https://lightmysky.com/learn/science/famous-dinosaur-species-mt_BnabTHkNIp)

## Optional connections

- [Plant-Eaters vs Meat-Eaters](https://lightmysky.com/learn/science/plant-eaters-vs-meat-eaters-mt_DJh2JPwTf6)

## Opens up

- [Reading Cladograms](https://lightmysky.com/learn/science/reading-cladograms-mt_cSPtyLF3q1)
- [Birds Evolved from Dinosaurs](https://lightmysky.com/learn/science/birds-evolved-from-dinosaurs-mt_T8JGTJ-oNI)